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941.
Edelmira García-Nieto Libertad Juárez-Santacruz Elvia Ortiz-Ortiz Héctor Santos Luna-Zendejas Dora María Frías-Márquez Hipólito Muñoz-Nava 《Chemistry and Ecology》2019,35(4):300-318
This study assesses the potential risk of Texcalac River and riparian area. The p,p′ DDT and ∑DDTs levels in agricultural soils (3.9–208.0?µg/kg) and in surface sediments (0.6–137?µg/kg) surpassing the guidelines for protection of aquatic life (75% > TEC). The ∑PCBs concentration oscillated from 135 to 93941?µg/kg; the half of sediments exceeded the international guidelines (PEL, PEC), as well as two soils (SQGE?=?500?µg/kg). The TEQ concentration of four PCB-DL varied between 0.1 and 24.9?µg TEQ/kg, chiefly affected by PCB 169. Five sediments were lethal for E. foetida, two resulted to be cytotoxic and the 58% produced genotoxicity higher than negative control (A?=?0.28?±?0.05; DICA?=?72.5?±?16.9 au). Likewise, 31.6% of samples increased the micronuclei frequency in V. faba in comparison with negative control. The analytical data and the bioassays results suggest a significant and immediate risk to exposed biota of this region, highlighting a specific area in Texcalac River and other one in Sambrano Ravine. It is necessity assess the dispersion of pollutants and perform biomonitoring studies that display the exposure levels in biota with the goal to characterise the ecotoxicological risk. 相似文献
942.
Ilić Aleksandra Prohaska Stevan Radivojević Dragan Trajković Slaviša 《Environmental Modeling and Assessment》2021,26(4):565-579
Environmental Modeling & Assessment - In confluence areas, where river flow slowdowns can be substantial, the selection of design flows for the purpose of designing a flood control system... 相似文献
943.
Abreu Murilo S. Kulczykowska Ewa Cardoso Sónia C. André Gonçalo I. Morais Marta Gozdowska Magdalena Soares Marta C. 《Behavioral ecology and sociobiology》2018,72(7):1-14
Behavioral Ecology and Sociobiology - A growing body of research suggests that songs are an important part of the courtship behavior of many bat species, however there is little information on the... 相似文献
944.
Mancera C El Mansouri NE Pelach MA Francesc F Salvadó J 《Waste management (New York, N.Y.)》2012,32(10):1962-1967
This paper studies the feasibility of incorporating treated lignins in fiberboards made from Vitis vinifera as an agricultural waste. The treated lignins are the purified Kraft lignin and the alkaline hydrolyzed Kraft lignin. V. vinifera raw material and its fibers were characterized in terms of chemical composition and the results were compared to other biomass species. The chemical composition of treated lignins shows that they have high purity compared to the lignin raw material. The lignin-V. vinifera fibreboards were produced on laboratory scale by adding powdered treated lignins to the material that had previously been steam exploded. Some of the important properties of fibreboards prepared using the treated lignins as natural adhesives were evaluated. These properties were density, thickness swelling, water absorption, modulus of elasticity, modulus of rupture, internal bond strength. The explored levels of treated lignins vary from 5% to 20%. The results showed that binderless fibreboards, fibreboards made from V. vinifera fibers and alkaline hydrolyzed Kraft lignin have weaker mechanical properties. However, the fibreboards obtained using purified Kraft lignin have good mechanical and water resistance properties which satisfy the requirements of the relevant standards specifications. 相似文献
945.
Francisco J. Arjona Ignacio Ruiz-Jarabo Luis Vargas-Chacoff María P. Martín del Río Gert Flik Juan M. Mancera Peter H. M. Klaren 《Marine Biology》2010,157(6):1325-1335
We have investigated the regulation of thyroidal status and osmoregulatory capacities in juveniles from the teleost Solea senegalensis acclimated to different ambient temperatures. Juveniles, raised in seawater at 19°C, were acclimated for 3 weeks to temperatures
of 12, 19 and 26°C. Since our preliminary observations showed that at 12°C feed intake was suppressed, our experimental design
controlled for this factor. The concentration of branchial Na+,K+-ATPase, estimated by measurements of enzyme activity at the optimum temperature of this enzyme (37°C), did not change. In
contrast, an increase in Na+,K+-ATPase activity (measured at 37°C), was observed in the kidney of 12°C-acclimated fish. In fish acclimated to 12°C, the hepatosomatic
index had increased, which correlated with increased plasma levels of triglycerides and non-esterified fatty acids. Plasma
cortisol levels did not differ significantly between the experimental groups. In liver and gills, the amount of iodothyronine
deiodinases that exhibit thyroid hormone outer ring deiodination was up-regulated only when fish did not feed. When assayed
at the acclimation temperature, kidney deiodinase activities were similar, indicating a temperature-compensation strategy.
3,5,3′-triiodothyronine (T3) tissue concentrations in gills and kidney did not differ significantly between experimental groups.
However, at 12°C, lower T3 tissue levels were measured in plasma and liver. We conclude that S. senegalensis adjusts its osmoregulatory system to compensate for the effects of temperature on electrolyte transport capacity. The organ-specific
changes in thyroid hormone metabolism at different temperatures indicate the involvement of thyroid hormones in temperature
acclimation. 相似文献
946.
Kurt Paschke Juan Pablo Cumillaf Sergio Loyola Paulina Gebauer Mauricio Urbina María Eugenia Chimal Cristina Pascual Carlos Rosas 《Marine Biology》2010,157(1):7-18
Episodes of hypoxia are common in the marine environment, and their ecological effects depend, in part, on their severity
and duration. Many species of decapod crustaceans reside in areas with fluctuating oxygen regimens. Physiological mechanisms
enhance the ability of these crustaceans to cope with acute episodes of hypoxia. Southern king crab, Lithodes santolla, fishery is important in the south of South America, and some data describe fishing zones with low dissolved oxygen (DO) levels
(3.5 mgO2 l−1, i.e., 8.3 kPa). Our main objective was to evaluate the effect of dissolved oxygen level on respiratory metabolism, nutritional
physiology, and immunological condition of L. santolla juveniles. Individual animals were exposed for 10 days to different oxygen tensions (2.1, 4.2, 8.5, 12.7, and 21.1 kPa) to
quantify the oxygen consumption rate; thereafter, blood oxyhemocyanin (Hc), protein concentration, as well as hemocytes, were
sampled. Freeze-dried animals were dissected, and digestive gland metabolites (glycogen, protein, glucose, cholesterol, acylglycerol,
and lactate) and digestive enzyme activity (general protease, trypsin, and chymotrypsin), as well as gill lactate dehydrogenase
(LDH) activity, were quantified. In the present study, Lithodes santolla showed a critical oxygen tension between 4 and 9 kPa, indicating that this crab species is more sensitive to DO than other
crustacean species. Protein and Hc concentrations followed a similar pattern to that of oxygen consumption. Digestive gland
glycogen and protein concentration did not change after 10 days at different oxygen exposures, but glucose, cholesterol, and
acylglycerol concentrations decreased linearly and proportionally to the available oxygen in the water. As in other decapods,
chymotrypsin showed over 90% of the total quantified proteases activity. Chymotrypsin activity together with total proteases
and trypsin was not affected by the environmental oxygen tension. Gill LDH and digestive gland lactate followed a similar
increase at lower environmental oxygen tension but dropped sharply at the lowest tension (2.1 kPa). Dissolved oxygen affected
also the immune system through reduction of hemocytes. This could provide a critical window for opportunistic pathogens to
become established when crabs are exposed to hypoxic conditions. L. santolla juveniles show a moderate tolerance to low oxygen availability by modifying the concentration of hemolymph proteins, mainly
OxyHc, some digestive gland metabolites, and by activating the anaerobic metabolism. This allows L. santolla juveniles to inhabit temporarily low oxygen zones in the deep ocean and suggests an advantage for culture conditions. 相似文献
947.
Andrés García José A. Juanes César Álvarez José A. Revilla Raúl Medina 《Ecological modelling》2010,221(8):1194-459
The aim of this study was to investigate the response to short-term changes in river freshwater discharges and in nutrients loadings (mainly from the treatment of urban wastewater), of the shallow macrotidal Urdaibai estuary (north of Spain), by using numerical tools. A two-dimensional hydrodynamic model and a water quality model were applied to the estuary, in order to better use it as a prediction tool in the study of the effects of variations in hydrodynamic conditions and in waste water inputs. The model was calibrated and verified using data measured under different hydrological conditions (spring and summer). A model calibration was carried out with field data measured during the summer, while the model validation was conducted for spring conditions. The calibration process allowed the model parameter definition, while the model validation permitted the verification of the calibrated parameters under different environmental conditions. The model results were in reasonable agreement with field measurements, in both the calibration and the validation phases. The model showed a significant decrease in phytoplankton concentration with river input increase. A study on the effects of nutrient input reduction from the Gernika Waste Water Treatment Plant (WWTP) was conducted. It showed a decrease in phytoplankton concentration with decreasing levels of nutrient discharge. This reduction was more pronounced in conjunction with the highest river discharge. In that case, a 50% decrease for the elimination of the WWTP discharge was observed. 相似文献
948.
While breeding synchrony among conspecifics is increasingly well understood with regards to the reproductive success of vertebrate
and invertebrate taxa, the occurrence of simultaneous multispecies breeding events remains intriguing. The fairly recent discovery
of mass annual spawnings in reef corals has provided a first glimpse at putative strategies of reproductive isolation during
such events. However, the mechanisms and advantages of same-day heterospecific breeding are still poorly understood and have
not yet been investigated in non-coral taxa with different life history strategies. In an effort to bridge this gap, we investigated
spawning periodicity and synchrony among 26 sympatric species of free-spawning, capsule-laying, and brood-protecting macroinvertebrates
belonging to six different phyla. Twenty-four of these species released gametes or larvae between early March and late April.
We analyzed the events over fine temporal scales to test the hypothesis that breeding activities were not random in time or
relative to each other. We found that the two main reproductive pulses followed a lunar periodicity and that consistent species-
and gender-specific modulations in the timing of spawning occurred during same-day episodes involving up to six free-spawning
species. Mass spawning accounts from the literature were reviewed and compared. This work suggests that many species participate
in synchronous heterospecific spawning events either because they respond to the same environmental cues or rely on cross-cueing
and that reproductive isolation is favored by species-specific circadian patterns, spawning behaviors and cross-gender signaling. 相似文献
949.
Anderson Ribeiro Duarte Luiz Duczmal Sabino José Ferreira André Luiz F. Cançado 《Environmental and Ecological Statistics》2010,17(2):203-229
The geographic delineation of irregularly shaped spatial clusters is an ill defined problem. Whenever the spatial scan statistic
is used, some kind of penalty correction needs to be used to avoid clusters’ excessive irregularity and consequent reduction
of power of detection. Geometric compactness and non-connectivity regularity functions have been recently proposed as corrections.
We present a novel internal cohesion regularity function based on the graph topology to penalize the presence of weak links
in candidate clusters. Weak links are defined as relatively unpopulated regions within a cluster, such that their removal
disconnects it. By applying this weak link cohesion function, the most geographically meaningful clusters are sifted through
the immense set of possible irregularly shaped candidate cluster solutions. A multi-objective genetic algorithm (MGA) has
been proposed recently to compute the Pareto-sets of clusters solutions, employing Kulldorff’s spatial scan statistic and
the geometric correction as objective functions. We propose novel MGAs to maximize the spatial scan, the cohesion function
and the geometric function, or combinations of these functions. Numerical tests show that our proposed MGAs has high power
to detect elongated clusters, and present good sensitivity and positive predictive value. The statistical significance of
the clusters in the Pareto-set are estimated through Monte Carlo simulations. Our method distinguishes clearly those geographically
inadequate clusters which are worse from both geometric and internal cohesion viewpoints. Besides, a certain degree of irregularity
of shape is allowed provided that it does not impact internal cohesion. Our method has better power of detection for clusters
satisfying those requirements. We propose a more robust definition of spatial cluster using these concepts. 相似文献
950.
Ana P. L. Batista Hudson Wallace Pereira Carvalho Gustavo H. P. Luz Paulo F. Q. Martins Maraísa Gonçalves Luiz C. A. Oliveira 《Environmental Chemistry Letters》2010,8(1):63-67
A photocatalyst based on CuO/SiO2 was prepared, and evaluated for the degradation of methylene blue in aqueous medium. The photocatalyst was obtained by calcination
method of copper salt, in the presence of silica. The characterization by XRD, FTIR, and TPR techniques confirmed the formation
of CuO as active phase. SEM studies showed CuO deposited on the surface of SiO2. By ESI-MS, it was demonstrated that the degradation of methylene blue occurs through successive hydroxylations. Photodegradation
assays showed that CuO/SiO2 was efficient for degradation, and that the material worked better in the presence of UV light. 相似文献